The invention discloses a steelmaking second-stage process control system and a steelmaking second-stage process control method. The steelmaking second-stage process control system is connected with an MES and receives operation indications issued by the MES, molten iron plan matching is carried out according to the actual performance of production, and real-time process data of production are obtained from a converter, a refining furnace and a continuous casting basic automation system in a fixed period mode in the production process. The steelmaking second-stage process control system comprises a production indication module, a progress management module, a production actual performance module, an ingredient management module, an operation actual performance module, an iron steel ladle management module, a standard management module and a statistic analysis module. According to the steelmaking second-stage process control system and the steelmaking second-stage process control method, a large number of data in all production line PLCs in an industrial net are safely and rapidly uploaded to the second-stage system in an office net, the aims of strengthening the management level of a steel mill, controlling the material consumption, reducing the cost of steel per ton and reasonably dispatching processes are achieved, and the economic efficiency and the whole competitive capacity of an enterprise are improved.